Air loaded valve



Aug. 6, 1940. J. H. FRIEDMAN AIR LOADED VALVE Filed 06,11. 18, 1938 2 Sheets-Sheet l INVENFOR. Jo A/ H. FwffD/wA/v.

ATTORNEY5 Aug- 6 1940- J. H. FRIEDMAN 2,210,236

AIR LOADED vALvE Filed Oct. 18, 1938 2 Sheets-Sheet 2 LQ i'v I J.

A TTORN E Y.5

Patented Aug. 6, 1940 UNITED STATES PATENT yori-"lola:

AIR LOADED VVALVE John H. Friedman, Tiin, Ohio, assigner to The National Machinery Company, Tiffin, Ohio, a

corporation of Ohio Application October 18, 1938, Serial No. 235,699

8 Claims.

This invention relatesto control valves and more particularly to a control valve actuated by a pilot or trip cylinder.

This invention' is particularly useful in connection with valves for controlling the clutch and brake of a forging machine, press or the like as disclosed, for example, in the copending application of William L. Clouse, Serial No. 64,530, led February 18, 1936, or a similar combination in which a valve for controlling pressure uid is operated by a pressure fluidlpilot cylinder controlled in turn by a trip valve.

In such devices the pressure fluid, usually compressed air, is obtained from a shop line vor other suitable source of supply and is admitted by operation of the trip Valve into the pilot cylinder, which overcomes the force of a return spring and moves the main control valve to admit pressure fluid to the clutch and Abrake operating cylinders,

or other devices to be controlled. In practicev manydifliculties are encountered, with this arrangement, primarily because the available pressure from the shop line or other source of supply varies through a relatively wide range while the action of the spring remains substantially constant. Any increase or decrease of the pressure from the valve for which the size of the piston and strength of the spring were selected changes the rate at whichy the valve ports are opened or closed, and likewisechanges the relative timing of the devices when two or more valves, such as the brake and clutch valves of a forging machine or press, are controlled by the same pilot cylinder.

The principal object of this invention is to provide a pilot or control motor for a control valve or the like in which the returning force against which the valve is moved is maintained at a constant ratio to the actuating force. Another object is to provide an actuating means for a plurality of control valves which open at different times in which the eiective actuating force is maintained at such a value during variations in the pressure supply as to maintain the relative timing of the parts controlled by the different Valves substantially constant. Other objects and advantages will appear in the following detailed description of the preferred embodiment of this forging machine or press.

Referring to the drawings the numeral I designates a valve casing or body which houses the control Valves and supports the Apilot cylinder. As illustrated, the sides of the housing are integral with the top wall 2 which is formed with a cored-out passage 3 extending from one side to the other of the top wall and around a central boss 4. The lower end of the housing I is closed by a bottom plate 5.

The unit illustrated embodies two control valves 6l and l, each of which is a three-way sleeve type compressed air valve. Any desired type of valves may be employed, and the invention is applicable to any desired number of valves. Each of the V valves 6 and 'I includes a central tubular member 8 which has Vits ends seated in opposed rabbets in the lower surface of the top wall 2 and the upper surface of the bottom plate 5 and is rmly clamped in position when the bottom plate 5 is secured to the casing I. The upper end of each'of the tubular members 8 opens directly into the passage 3 formed in the top wall 2. The lower ends of the tubular members 8 of the valves I5 and 'I open into passages 9 and I0, respectively, formed in the bottom wall 5. Each 2 of the tubularmembers 8 is provided with a central partition II and series of ports I2 and I3 above and below the partition, respectively. The interior of the casing I is, open to atmosphere through a port I4. 30

A valve sleeve I5 slidably surrounds each oi' the tubular members 6 and l. Each sleeve I5 has its central portion spaced from the tubular member upon which it is mounted and is provided with end walls I6 engaging the outer surface 35 of its respective tubular member and carrying suitable packing to prevent escape of pressure fluid. The sleeves I5 in their uppermost positions,

`as illustrated inthe drawings, cover and close the ports I2 Iin the upper portion of the tubular member 6, leaving 'the ports I3 open to the interior of the casing I and thus to atmosphere through the port I4. When vthe'tWo sleeves I5 are moved downwardly to their lowermost position they span' the partitions II and establish communicationV between the portsV I2 and I3 of each valve. The two sleeves I5 are connected to an operating rod or valve stem` I1 which is slidably supported in an opening in the boss 4 of the top wall 2 and an aligned opening in the bottom wall 5.` f

The valve actuating motor comprises two opposed pistons of different areas, the smaller being constantly open to the line pressure and the larger being opened alternately to line pres- 55 lll sure and atmosphere by a trip valve. In the illustrated embodiment, a casing I8 is supported below the bottom wall 5 and is provided with upper and lower cover plates i9 and 2li. The upper portion of the casing I8 is formed with a cylinder bore 2H and the lower portion with a cylinder bore 2?; of smaller diameter. A piston 23 slidably fits Within the cylinder bore 2l and is formed with a reduced piston extension 211 slidable within the reduced cylinder bore 22. The valve stem I1 extends through a packed opening in the upper cover plate I3 and is provided with a reduced lower end 25 extending through thev` pistons 23 and 24. A nut 25 secures the pistons 23 and 24 to the reduced end 25 of the valve stem, and also serves, in the illustrated embodiment, to secure suitable packing 21 to the upper surface S the piston 23 and the lower surface of piston A port 28 is formed in the upper cover plate l opening into the cylinder bore 2! above the piston 23 and communicating with a pipe 23. A conduit 3B is supported by suitable fittings `so as to communicate at its upper end with the passage 3 formed in the top wall 2 ,of the valve casing and at its lower end with a port 3l opening into the lower cylinder bore 22 below the reduced piston 2d.

In Figure 2 the control unit is shown arranged to be used to control a forging machine, press .or the like, as illustrated in the aforesaid application of Clouse, Serial No. 64,530, iiled February 18, i935. In such machines a combined friction clutch and flywheel 32 is rotatably mounted upon a driven shaft 33, the opposite end of which carries a brake drum3. The driven shaft 33 is geared to a main shaft 35,' one end of which carries a cam 33 which co-operates in controlling the valve mechanism. In Figure 2 these parts are shown developed in order to more clearly illustrate the relation between the valve, the clutch and the brake, although it will be understood that the brake, clutch and cam can be mounted at any desired points in the machine.

The flywheel and friction clutch 33 may be df the construction illustrated in detail in the copending application of William L. Clouse, 'erial No. 31,251, filed July 13, 1.935, to which reference is made for a detailed disclosure of one form of combined flywheel and clutch. The clutch includes friction elements which are arranged to be pressed together to couple the flywheel and clutch casing to the driven shaft when fluid pressure is admitted through a central connection 31 and to be released when the fluid pressure is exhausted through this connection. Ordinarily a motor or other source of power is belted or geared to the flywheel and clutch 32 to continuously rotate the same.

The brake mechanism illustrated embodies a brake band 38 surrounding the drum 34 having,r its free end connected to a piston 39 reciprocable in a cylinder dll. A spring lll normally maintains the band 38 tightly engaged about the drum 312 so as to hold the shaft against rotation. When fluid pressure is admitted to the cylinder 4i) through the pipe 42 the piston 39 is moved against the pressure of the spring 4l to release the brake band.

Compressed air from a main supply line 43 is preferably conducted first to a reservoir M to provide a sufficient volume of compressed air adjacent the machine to prevent excessive fluctuations of the pressure. A supply pipe 45 leads from the reservoir A4 to the passageS of the valve housing. A branch pipe 46 leads from the pipe l5 to a trip valve 41, to which is also connected the pipe 29 and an exhaust 48. The trip valve lil may be any convenient form of three-way valve arranged to connect the pipe 29 with the supply line d5 when depressed and with the exhaust i3 when released. A pipe AS is connected to the passage I3 in the bottom plate 5 of the valve casing and to the center connection 31 of the friction clutch 32. The pipe 62 leading to the brake releasing cylinder It@ is connected to the passage 9 in the bottom plate 5.

The upper end of the valve stem I1 carries a in 5t loosely fitting in an opening in a link 5I pivoted at 52 'to a portion of the machine frame or the like. The link 5I also carries a roller 53 serving as a cam follower and engaging the periphery of the cam 36.

In the initial position of the parts the combined friction clutch and iiywheel 32 is freely rotating upon the driven shaft 33 while the driven elements of the machine are held stationary by the brake band 3B. The strip valve 41 is in its released position so that the pipe 29 and the cylinder 2l are open to atmosphere and the fluid pressure in the cylinder 22 holds the Valve stem l1 in its uppermost position. When the trip valve l1 is operated pressure fluid is admitted from the supply tankfil through the pipe 29 to the cylinder 2l which overcomes the pressure in the cylinder 22 and moves the valve stem l1 downwardly. As the valve sleeves I5 move downwardly the ports i3 in the valve are first closed to atmosphere and thenyplaced in communication with the ports l2. Pressure-is thereby admitted from the passage Si through the tubular member 8, the iassage 9 and the pipe 42 into the cylinder 4B, forcing the piston 33 to move against the spring lli and release the brake band 33. Further downward movement of the valve stem l1 causes the sleeve l5 of the valve l' to admit compressed air from the passage 3 through the passage I3, the pipe 29 and the connection 31 to the friction clutch 32, causing engagement of the clutch. The driven elements of the machine are thereby connected to the rotating flywheel and clutch 32 and the machine is set in motion.

The downward movement of the valve stem l1 to open the valves has drawn the roller 53 away from the cam 33. As the shaft 35 starts to rotate the high` part of 'the cam 33 moves into engagement with the roller 53 and holds the valve stem l1 down. While the valve stem l1 is heldy down by the cam 36 the trip valve l1 is released, ex-

hausting the cylinder 2l to atmosphere so that .y

the roller 53 is pressed against the cam 3B by the pressure in the cylinder 22. When the shaft 35 has completedrone revolution the cam 36 permits the valve stem l1 to ride upwardly under the influence of the pressure in the cylinderw22 and close the valves in succession, the two valve sleeves l5 acting rst to exhaust the pressure in the friction clutch 32 and then to exhaust the pressure in the brake cylinder 40 permitting the spring 2l to apply the brake and stop the driven elements of the machine with the parts inthe relative positions illustrated in the drawings.

It will be apparent that when the reduced piston 24 is forced downwardly by the air pressure admitted above the piston 23 the air contained in the cylinder bore 22 is forced backwardly through the conduit 3D without changing the pressure exerted against the reduced piston 24. A differential between the pressures of the pistons 23 and 2B is always present when pressure fluid is ad-` 75 area than size of the pistons 23 and 24.

'mitted to the upper side ofthe piston 23 because `source of pressure and the piston 24 has a smaller the piston 23, this differential having a ratio to the line pressure which remains constant and which is determined by the relative During the `opening of the valves any desired relative timing between the points at which the two valves open may be obtained by the relative positionsiof the ports I3 in the two valves so long 'as the actuating pressure remains constant. 'KWith a given pressure this timing is selected so that as soon as the air pressure has released the brake the clutch is engaged, thereby preventing any possibility of the clutch and brake being in engagement at the same time and also minimizing the time loss between the actuation of the trip cylinder and the starting of the machine. However, the time required for the air pressure to release the brake after the brake valve is opened varies with any variations in the pressure of the compressed air supply. Likewise the force applied to the piston 23, and therefore the speed at which the valve stem l1 operates, varies With Variations in the pressure of the air supply. Where a spring is employed to return the valve stem I1 the effective actuating pressure to open the valves does not vary in proportion to the variations in the pressure supply line, and as a consequence an increase in the pressure over that for which the valve is initially timed may result in the clutch starting toengage before the brake is fully released, whereas a decrease in pressure causes an excessive delay during the opening of the clutch valve so that excessive slippage of the clutch takes place. By loading the valve stem I1 from the main pressure supply line by means of the reduced cylinder 22 the effective actuating pressure for moving the valves retains a constant ratio to the pressure in the supply line so that the necessary timing between the clutch and the brake is maintained, and at the same time the clutch valve is opened with the maximum possible speed to admit the full line pressure into the clutch and minimize slipping.

In the illustrated embodiment a space 54 is formed below the main piston 23 and above the reduced cylinder 22. If desired this space may be left closed to serve as a cushion to prevent any shock at the end of the travel of the valve stem l1, or it may be provided with one or more bleed openings 55. The openings 55 may be made sufficiently small to enable the air trapped in the space 54 to check or cushion the movement of the stem I1, while at the same time avoiding any possibility of an excessive air pressure being built up in the space 54.

Although a preferred embodiment of the invention has been described in detail, it will be understood that many variations 'and modifications may be resorted to without departing from the scope of the invention as dened in the following claims. Although the particular construction disclosed is designed for operation with compressed air, it will be understood that the invention is also applicable to other pressure uids and also to other machines or devices than the particular type of machines specifically referred to.

' I claim:

1. In combination, a uid actuated clutch, a iiuid pressure supply, a valve for controlling the admission of pressure fluid from said supply to said clutch, a cylinder in constant communication with said fluid pressure' supply having a piston operatively connected to said valve tending to move the same t'o closed position, andv means for opening said valve against the force of said piston.

2. In combination, a fluid pressure clutch,V a fluid pressure brake, a source of supply of pressure fluid, valve means arranged when moved to open position to admit pressurefiuid from said supply successively tosaid brake and said clutch, a cylinder in constant communication with said` fluid supply having a piston normally urging said valve means to closed position, and a pilot cylinder having a piston arranged to move said valve means to open position against the force of said rst named piston. l

3. In combination with an intermittently operated machine having a uid pressure actuated clutch, a fluid pressure supply, a valve for controlling the admission of pressure iiuid from said supply to said clutch, means operated by fluid from said uid pressure supply constantly urging said valve to closed position, means for opening said valve, and means controlled by said machine for holding saidfvalve open and permitting the same to close after a predetermined operation of said machine under the influence of said rstnamed means.

4. In combination with an intermittently operated machine having a fluid pressure actuated clutch, a uid pressure supply, a valve for controlling the admission of pressure uid from said supply to said clutch, means operated by'fluid from said fluid pressure supply constantly urging said valve to closed position, means for opening said valve, and a cam on said machine holding said valve open during a predetermined operation thereof and thereafter permitting said valve to close under the influence of said first-named means.

5. In combination with an intermittently operated machine having a fluid pressure actuated clutch, a fluid pressure supply, a clutch valve for controlling the admission of pressure iiuid from said supply to said clutch, means operated by fluid from said fluid pressure supply constantly urging said clutch valve to closed position, a fluid actuated motor operatively connected to said clutch valve, a trip-valve arranged in one position to admit fluid from said fluid pressure supply to said motor to open said valve and in another position to exhaust said motor, and means controlled by said machine for holding said clutch valve open after the exhausting of said motor and permitting the same to close after ya predetermined operation of said machine under the influence of said first-named means.

6. In combination with an intermittently operated machine having a fluid pressure actuated clutch, a fluid pressure supply, a clutch valve for controlling the admission of pressure fluid from said supply to said clutch, means operated by fluid from said fluid pressure supply constantly urging said clutch valve to closed position, a uid actuated motor operatively connected to said clutch valve, a trip valve arranged in one position to admit fluid from said iuid pressure supply to said motor to open said clutch valve and in another position to exhaust said motor, and a cam on said machine holding said clutch valve open during a predetermined operation of the machine and during the exhausting of said motor, and thereafter permitting said clutch valve to close under the influence of said means.

7. In combination, an energy controlling uid actuated friction clutch, a source of supply o f pressure uid, a valve for controlling admission of uid pressure from said supply to said clutch, a cylinder in constant Communication with said supply of pressure fluid having a piston urging said valve to closed position, a cylinder of larger cross section than said irst named cylinder having a piston arranged to move said valve to open position against the force of said first named piston, and manually controlled means for conv necting said second named cylinder to said supply of pressure fluid.

8. AIn combination, a driving member and a driven member, a luid actuated friction clutch arranged to couple said driving and driven memz bers, a fluid actuated brake for said driven member, a source of supply of pressure fluid, a clutch valve for controlling the admission of fluid from said supply to said `clutch,a brake valve for controlling the admission of fluid from said supply to said brake, a cylinder in constant communication with said supply of pressure fluid having 4a piston connected to both of said valves constantly urging the same to closed position, a second cylinder of larger cross section than said rst named cylinder having a piston connected to both of said valves and arranged to move the same against the force of said iirst named piston to open rst the brake Valve to release said brake and thereafter to open said clutch valve to engage said clutch, and manually controlled means for admitting fluid from said supply to said second cylinder.

JOHN H. FRIEDMAN. 

